[from George Bush Sr.'s “voodoo economics”]
1. The use by guess or cookbook of an obscure or hairy system, feature, or algorithm that one does not truly understand. The implication is that the technique may not work, and if it doesn't, one will never know why. Almost synonymous with black magic, except that black magic typically isn't documented and nobody understands it. Compare magic, deep magic, heavy wizardry, rain dance, cargo cult programming, wave a dead chicken, SCSI voodoo.
2. Things programmers do that they know shouldn't work but they try anyway, and which sometimes actually work, such as recompiling everything.